Endotracheal tube



Dec. 2, 1969 J. A. MILLET PUIG 3,481,339

ENDQTRACHEAL TUBE Filed March 28, 1968 F/Zz/ BY M P w,

ATTORNEY;

United States Patent 3,481,339 ENDOTRACHEAL TUBE Jorge Alberto MilletPuig, 2336 Sarmiento St., Castelar, Buenos Aires, Argentina Filed Mar.28, 1968, Ser. No. 716,752 Claims priority, applicaztgzn Argentina, Apr.10, 1967,

Int. 01. A61m 25/02, /00

U.S. Cl. 128-351 4 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THEINVENTION Field of the invention The present invention refers to anendotracheal tube for the ventilation of the lungs, to be used inoperations and also for prolonged treatments.

Description of the prior art To facilitate the ventilation of the lungs,in certain circumstances, and to carry out a number of operationalsteps, it is necessary to place a tube or cannula into the trachea. Thisrequirement is more demanding in all those cases where there isbreathing trouble or paralysis; for example in certain diseases(poliomyelitis), traumatisms (specially of the cranium or thorax) orduring operations.

There are two different procedures, tracheotomy and endotrachealintubation, for inserting the tube or cannula, the selection of whichdepends on the particular case. The first requires, in itself, anoperation, the purpose of which is to directly communicate theendotracheal space with the outside, to which end an incision is made atthe base of the throat and extending into the inner cartilage wallportion of the trachea to insert therethrough the tube. The insertioncould be temporary or permanent. Once this operation has been carriedout, the air or gases at the entrance or exit of the lungs need nolonger circulate through the so-called upper airways (upper portion ofthe trachea, larynx and mouth or nose).

The endotracheal intubation, on the other hand, is bloodless, and iscarried out by using one of several known techniques and differentauxiliary devices (laryngoscope or bronchoscope). Here, the tube isintroduced through the upper airways (mouth or nose, larynx and trachea)without the need for an incision. In this case the aforementioned tubeis used.

Although sometimes a distinction is made between canula and tube for thepurpose of this invention, these expressions are considered to besynonymous. Some experts also use the term catheter.

In the two above mentioned cases (tracheotomy and endotrachealintubation) it may be necessary to form a seal between the endotrachealtube or cannula and the inside of the tracheal wall so as to obtain tworesults. On the one hand, the isolation of the respiratory organs fromthe feeding tract, such as in the case of dysphagia, to avoid theaspiration of secretions, regurgitations, etc. On the other hand, in thecase where artificial respiration,

either by intermittent positive pressure or alternate positive-negativepressure, is required.

To obtain this seal, endotracheal canules or tubes are universally usedwith a cuff placed close to the lower end, inflatable once in place.

Even though the use of these known cuffed tubes provides advantages,there are a number of drawbacks which can have very serious or evenmortal consequences for the patient. As regards this, J. Mck Wattsstates the following, in his paper Tracheotomy in Modern Practice (TheBritish Journal of Surgery 50; 954-975; (1963) for which he received inEngland in 1962, the Moynihan prize.

The major problem in the use of an inflated cuff in the trachea is itsliability to produce pressure necrosis of the mucous membrane (page969).

To avoid this serious complication, amongst other expedients, heproposes a minimum possible distention of the cuff, allowing it tocollapse during several minutes every hour.

In another chapter of his paper, when reviewing the possiblecomplications arising in a tracheotomy, he emphasizes:

The complications of tracheotomy; 5 Pressure effects of tracheotomytubes: (c) Pressure on the tracheal wall by an inflated cuff in thelumen.

It is of vital importance, in the use of inflated cuffs in the tracheato attempt to prevent pressure necrosis of the tracheal mucosa. Themethods used have been described. Beaver (1961) reports the absence ofpressure complications following the use of inflated cuffs, but ourexperience has not been so fortunate in following the use of the Jamestube. This tube was used on 19 occasions between 1953 and 196.0 but inonly 4 patients was the trachea examined following the removal of thetube. Of the four trachea examined, two had extensive anterior andposterior tracheal wall ulceration at the site of the cuff. In another,a severe tracheal stenosis developed at the site of the cuff, and thispatient now has a permanent tracheotomy and requires repeated trachealdilatation.

Two further tracheas have recently been examined at autopsy followingthe use of the James tube. Posterior wall ulceration was present in one;in the other a circumferential tracheal stenosis was present at the siteof the cuff.

From what can be seen from the above, the known tubes including aninflatable cuff, required the distention of said cuff, once the tube hadbeen inserted in the trachea, so as to immobilize the tube, and producean isolation between the upper and lower portions of the trachea.

This distention was produced by directly inflating the cuff through anair injecting tube connected to the cuff. The distended cuff producedthe lesions previously analyzed.

The cult must be inflated in such a way that the pressure in it islarger than the maximum endotracheal pressure that the patient iscapable of generating and which corresponds to the maximum pressurelevel. If these steps are now followed with the known devices, themaximum endotracheal pressure would compress and collapse the inflatedcuff and this would destroy the seal-tight anchorage of the tube in thetrachea. The pressure which has to be generated in the cuff necessarilyreaches such a high level as to interrupt the blood circulation throughthe trachea tissues, pressurized by the cult, thereby producing thelesions already analyzed.

Taking into account the tubes and canulas already known prior to thepresent invention, with a view to overcome in every possible way all thedrawbacks just mentioned, it has been proposed that the pressure in thecuff be diminished now and then at regular intervals, to 'momentaneouslypermit circulation of the blood through the tissues surrounding thecuff. If these decompressions are to be carried out during an operation,a highly expert person is required to perform this task, since, if thedecompression is excessive, the tube is apt to be moved out of positionand could even produce the drainage of certain accumulated substancesfrom one or other side of the cuff, that would create difficulties inthe patients breathing.

It is obvious that before each decompression the foreign matteraccumulated on the cuff should be suctioned out.

It has also been suggested that tubes With successive cuffs be used, sothat successive compression can be carried out in different parts orportions corresponding to each cuff. In this case also the assistance ofan expert i required and in practice, these tubes with two cuffs havenot shown good results, since in many cases, the length of the tube thatis surrounded by the two cuffs can produce bronchial occlusion andfurther consequences. Also, the accumulation of secretions that areproduced between both cuffs are diffcult and sometimes impossible to besuctioned out, producing the same difficulties as in the case previouslyanalyzed.

SUMMARY OF THE INVENTION The idea on which the present inventon isbased, is that a tube should be provided having a cuff for maintainingthe tube in its proper position, but which also guarantees that theblood circulation through the tissues surrounding the cuff is notinterrupted for a longer period of time than it takes to change frominspiration to expiration during each breathing cycle. In this way,normal conditions are maintained in the tissues, exempting them from theformation of ulcerations or any other type of the aforementioneddeterioration. To achieve this objective, it has been thought to makeuse of the variations in pressure provided by the patient himself duringbreathing, using as a point of reference the moment of minimumendotracheal pressure to additionally create a minimum necessarypressure in the particular cuff of this invention, so as to immobilizethe tube lodged in the trachea. Also, the inspiration step is used toincrease the pressure in the cuff, as shall be explained later on. Inthis way, a certain massage is carried out on these tissues and aperfect isolation is gained between the two tracheal zones separated bythe cuff.

More particularly, the invention refers to an endotracheal tube for thepulmonary ventilation, applicable during surgical operations as well asfor prolonged treatments. The endotracheal tube is of the type includinga main tubular member open at both ends, a cuff surrounding anintermediate portion of said main tubular I member adjacent to one ofits end portions, the edges of said cuff being sealed to spaced-apartzones. of said intermediate portion of said main tubular member, andsaid cuff defining with said intermediate portion of said main tubularmember a chamber. An additional tubular air injecting member isconnected to said cuff. The invention is characterized in that at leastone part of said intermediate portion of said main tubular member issurrounded by an inflatable bag, which sealingly divides said chamberinto an external subchamber and an internal sub-chamber, and saidintermediate portion of said main tubular member having at least oneopening facing said internal sub-chamber.

In one of its preferred embodiments, the endotracheal tube of thepresent invention, may have more than one opening that faces saidinternal sub-chamber and said openings should preferably be elongated toavoid obstruction, facilitating at the same time, the cleaning of thedevice.

The edges of the bag are preferably linked in the same zone as the edgesof the cuff to the intermediate portion of said main tubular member.

As regards the air injecting tube, this can be externally disposed tothe main tubular member, or could also be arranged within this maintubular member. The remote end portion of the injecting tube ispreferably provided with a globe known as pilot through which thesurgeon or his assistant can easily detect if there is pressure in theexternal sub-chamber.

BRIEF DESCRIPTION OF THE DRAWINGS So as to facilitate the understandingof the present invention, reference will now be made to a specificembodiment by way of example, in relation to the accompanying drawings,wherein:

FIG. 1 is a schematic representation, partially in section, of anendotracheal tube in accordance with the present invention, and which isshown as inserted in a trachea.

FIG. 2 is a diagram of cuff pressures for an endotracheal tube of theknown type, that does not include the bag that forms part of the presentinvention.

FIG. 3 is a diagram of cuff pressures for an endotracheal tube inaccordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, reference numeral 1,identifies a schematically illustrate-d human trachea. The lower end ofthe trachea 1 is likewise shown, as dividing into branches 2 and 3leading to the left and right lungs respectively. Upon having to carryout an operation as is already known by those skilled in the art, anendotracheal tube is inserted in the trachea of the patient so that thelower end of said tube remains close to the bifurcating branches 2 and3. In the embodiment shown of the endotracheal tube of the presentinvention, the former comprises a main tubular member 4 having a lowerend 4' arranged adjacent the bifurcating branches 2 and 3. The upper endof the main tubular member 4 is not shown, as being of no interest tothe present invention, bearing in mind that the upper end is also open,although it may be connected to any additional device.

An intermediate portion of the main tubular member 4, adjacent the lowerend portion 4', which intermediate portion is identified by referencenumeral 5, is surrounded by a cuff 6 having an upper edge 7 and a loweredge 8, both usually of the reinforce-d type and sealed to spaced-apartzones of said intermediate portion 5 of said tubular member 4. It cannow be appreciated that the cuff 6 defines with the external face of theintermediate portion 5 a chamber which, as will later be seen, isactually divided into two sub-chambers.

In the most current known structures of endotracheal tubes, thearrangement so far described is provided with a cuff, where the insideof the intermediate portion 5, forming part of the conduit defined bythe main tubular member, is not connected to the chamber defined by thecuff 6. This cuff 6 is connected to an additional tubular injectingmember 9, the outer end of which can for example be connected to thealready cited pilot globe 10. A structure of this type, without takinginto consideration the other means to be described further on, and whichwould be then a known structure, requires, to immobilize theendotracheal tube, that a quantity of air is injected through theadditional injecting member 9 until the cuff sufficiently anchors theendotracheal tube in the trachea, even though outstanding momentaryoverpressures are generated, such as when the patient coughs. As isalready known, the volume of air to be inflated in such a case is solarge that the cuff 6 oppresses the trachea 1, whereby blood circulationto the tissues is obstructed in the oppressed zone.

In accordance with the present invention, the intermediate portion 5 ofsaid main tubular member 4 has at least one opening in the embodimentshown, such as the two elongated openings 11.

Furthermore, the zone in which these openings 11 are located, issurrounded and hermetically enclosed in an inflatable bag 12 thatdivides the already cited chamber into an external sub-chamber 13'and aninternal subchamber 14, which are sealed from each other.

In fact, in the embodiment shown, the edges of the bag 12 are alsosealed to the edges 7 and 8.

Obviously, the bag could also have its 'own edges, spaced-apart from theedges 7 and 8, and be placed closer to the openings 11. t

It should still be pointed out that the edges 7 and 8 in the embodimentillustrated, could rigidly be linked to the intermediate portion 5 orcould be resiliently gripped thereto so that each edge defines a sealedcollar. The resiliently gripping collars are preferred since theyfacilitate the cleaning of the instrument, i.e. the cuff and bagassembly 6, 12, can be easily removed from the main tubular member 4.

Before analyzing the operational behaviour of the endotracheal tube inaccordance with the present invention, it is convenient that somecomments are made with regard to the respiratory cycle.

The entrance and exit of gases in the respiratory al velous or cavitiesof the lung, depend on-the variations in internal lung pressure inrelation to the room pressure.

During natural or spontaneous respiration, the entrance of gases(inspiration) into the lungs is produced due to the reduction ofinternal lung pressure produced by the increase of thoracic volumeformed by the contraction of the respiratory muscles. The loosening ofthese muscles causes a decrease in the volume of the thorax, withpulmonary compression and an increase of the endotracheal pressure thatstresses and expels the internal lung gases (expiration) If for anyreason (save obstruction of the superior airways) there is an alterationin the normal cycle of inspiration and expiration, an emergency isproduced, which becomes the more outstanding as the respirationdecreases.

In cases of paralysis of the respiratory system, it is considered thatafter 3 minutes having passed, signs of irreversible cerebraldeficiences start to show, producing death within more or less shortperiods, but always within minutes.

To counteract such emergencies, taking into account the causes and theelements at hand, apparatus are used that modify the room pressures(e.g. pulmotor or iron lungs) or endotracheal tubes (mechanicalrespirators) which act by air or other gas injections.

Depending on the device used, variations of the intertracheal pressureare similar (pulmotor and iron lungs) or reverse (mechanicalrespirators) to the spontaneous respiration.

If known type of endotracheal tube is used, similar to the presentinvention, but without the bag 12, and the openings 11, the cuffcorresponding to cuff 6 is inflated, through the additional tubularinjecting member 9 until expanding the cuff sufficiently to generateradial pressure on the surrounding tissues with a view to obtain at alltimes, the sealing off of the respiratory cycle, including those casesin which there is accidental over-pressure (cough). If FIG. 2 isanalyzed where the ordinate axis Y indicates pressures and the abcissaaxisX indicates time, the curve R represents the respiratory cycles ofthe patient. More particularly, the ascendant curved portion R indicatesthe inspiration which reaches its maximum at peak M to diminishthereafter as shown by curve R corresponding to expiration whichobviously reaches, in the final portion of the cycle, beneath theatmospheric pressure. For anchoring the cuff of the known devices, inthe trachea, it is necessary to inflate the edit with air untilgenerating a constant pressure larger than peak M, which pressure isshown by the horizontal line P.

On the other hand, by using the present invention, as

shown in FIG. 3, where the ordinate Y, the abscissa X and the curve Rcorrespond to the same concepts as those shown in FIG. 2, curve R whichcould also be defined as representing the variations of intertrachealpressure. These pressures are freely transmitted to the internalsubcharnber 14 (FIG. 1) through the openings 11, thereby increasing anddecreasing the size of the bag 12, in accordance with the variation ofthe cycle of the curve R. To anchor the tube in the trachea, it isnecessary to inflate air into the external sub-chamber 13 through theadditional tubular injecting member 9, until a final pressure isachieved, which is the sum of the proper pressure in the externalsub-chamber 13 plus the pressure that is generated in the internalsub-chamber 14, during the expiration stage, which is sufficient toanchor the tube and provide the necessary sealing. This pressure isdefined by the height A shown in the FIG. 3. As the pressure in thethorax increases and thereby the endotracheal pressure during theinspiration step, the pressure of line P also increases and which inFIG. 3 is not constant, as in FIG. 2, Thus, the resulting pressure inthe cult is always the same or only slightly greater than the pressurereigning in the trachea.

Thus it can be appreciated that a slight over-pressure in the externalsub-chamber 13 is enough to assure a seal with low pressure on thetracheal wall during the major part of the respiratory cycle, whichpressure automatically increases any time the pressure increases in thetrachea, which results in maintaining the seal.

Giving a practical example, it could be said that normally the pressureproduced by the respiratory cycle varies between +20 and 4 cm. of watercolumn. The previously known endotracheal tubes have only one cuff, musttherefore be inflated until reaching a pressure that will assure theseal at a pressure of at least +20 cm. of Water column.

On the other hand, by using the endotracheal tube of the presentinvention, air is inflated into the external subchamber 13 until apressure is reached which is suflicient to maintain the seal between theinternal face of the trachea and the external face of the cuff, uponreaching a minimum pressure of 4 cm. of water column in the respiratorycycle.

As the endotracheal pressure increases, which tends to collapse the cuff6 since there would not be sufficient pressure inside it, this pressureis automatically increased due to the additional pressure supplied bythe patient himself inflating the internal sub-chamber 14.

Therefore, the pressure exerted on the trachea through the cuff 6 isonly substantially increased, upon the respiratory cycle reaching itspeaks.

It is obvious that within the spirit and scope of the present invention,several changes and modifications may be suggested. Thus, to avoid thatthe tubular member 4 in the portion above the cuff 6 enters intofrictional contact with the trachea tissues, it may prove advisable incertain cases to enlarge the length of the cuff 6 and eventually of theinflated bag 12 to cover substantially the entire length of the portionof the tubular member which is to be inserted in the trachea. Analternative suggestion along these items of avoiding frictionalengagement, would be to provide two arrangements of the combined type ofcuff and bag, which arrangements are to be located, one adjacent thebranches 2 and 3 and the other spaced-apart from the first one adjacentthe other open end of the tubular member.

This last arrangement has not yet been tested so that certain drawbacksof the type already described in connection with the evacuation ofsecretions may arise.

What is claimed is:

1. In an endotracheal tube for the ventilation of the lungs, applicableduring operations as well as for prolonged treatments, of the typecomprising a main tubular member having an intermediate portion and twoends, said main tubular member being open at both ends, saidintermediate portion having two spaced apart zones, a cutf surroundingsaid intermediate portion of said main tubular member, said cufi havinga pair of spaced apart edges, said edges of said cuif being each sealedto one of said spaced-apart zones of said intermediate portion of saidmain tubular member, said cufi defining with said intermediate portionof said main tubular member a chamber, an air injecting tube connectedto said cuff, at least one part of said intermediate portion of the maintubular member being surrounded by an inflatable bag that divides saidchamber into an external sub-chamber and an internal sub-chamberisolated from each other, and said intermediate portion of said maintubular member having at least one opening facing said internalsub-chamber.

2. An endotracheal tube in accordance with claim 1, wherein said cuffsurrounds said main tubular member close to one of its ends.

3. An endotracheal tube in accordance with claim 1, wherein said bag hastwo opposite edges joined to said spaced apart edges of said cuff,thereby forming reinforced edges sealed to the intermediate portion ofsaid main tubular member.

4. An endotracheal tube in accordance with claim 2, wherein saidintermediate portion of the main tubular member has two elongatedopenings.

References Cited UNITED STATES PATENTS OTHER REFERENCES Martinez, Jour.Thoracic & Card. Surg., vol. 47 #3, March 1964, pp. 404-405.

DALTON L. TRULUCK, Primary Examiner US. Cl. X.R. 128--208

